Purification of air

Abstract

An air purification system for purifying recirculated air eg in an aircraft, vehicle, offices or hospitals comprises the combination of a filter section with an ultraviolet illumination section and a coating of an antimicrobial agent on surfaces in one or both of the filter and illumination sections. Air flow through the illumination section is caused to be slightly turbulent by means of a multi-bladed fan being fixed in position between the filter and illumination sections. This increases the dwell time of contaminants in the illumination section. The antimicrobial agent includes as an active ingredient a quarternary ammonium salt and preferably as the following structure.

1 . A method of purifying air comprising withdrawing air from an enclosed space, passing the withdrawn air over surfaces coated with an antimicrobial agent, through an ultraviolet radiation and returning the thus irradiated air to the enclosed space.  
     
     
         2 . A method according to  claim 1 , and comprising filtering the withdrawn air.  
     
     
         3 . A method according to  claim 1 , and comprising causing turbulence to the air flow prior to passing the withdrawn air through ultraviolet radiation.  
     
     
         4 . A method according to  claim 1 , wherein the antimicrobial agent includes as an active ingredient a quarternary ammonium.  
     
     
         5 . A method of purifying air substantially according to  claim 1 , wherein the antimicrobial agent includes as an active ingredient a compound having the following structure  
       
         
           
           
               
               
           
         
       
     
     
         6 . Apparatus for purifying air comprising means ( 3 ) for withdrawing air from an enclosed space ( 1 ), ducting ( 4 ) for directing withdrawn air through a unit including an ultraviolet radiation section ( 5 ) for irradiating the withdrawn air and thence back to an air inlet ( 8 ) arranged to communicate with the enclosed space, the unit having at least one of its internal surfaces coated with an antimicrobial agent.  
     
     
         7 . Apparatus according to  claim 6 , and comprising a filter ( 6   a ) for filtering the withdrawn air.  
     
     
         8 . Apparatus according to  claim 6 , and comprising means ( 6   b ) for causing the air flow to separate into a number of various paths in order to cause turbulence in the air flow.  
     
     
         9 . Apparatus according to  claim 7  or  8  wherein the antimicrobial agent is coated on at least some of the internal surfaces of the filter ( 6   a ) and/or the air flow separating means ( 6   b ).  
     
     
         10 . Apparatus according to  claim 6 , wherein the antimicrobial agent includes as an active ingredient a quarternary ammonium salt.  
     
     
         11 . Apparatus according to  claim 10 , wherein the ammonium salt has a nitrogen atom substituted by a silane group.  
     
     
         12 . Apparatus according to  claim 11 , wherein the silane group is attached to the nitrogen atom of the salt by a propyl group.  
     
     
         13 . Apparatus according to  claim 6 , wherein the antimicrobial agent includes as an active ingredient a compound having the following structure: